SOURCE

load();

<div id="main">
  <div id="header">
    <div style="position:relative;top:+20px;left:0px;">
      <g:plusone size="medium">
      </g:plusone>
    </div>
    <p id="mp1">
      二维码扫描
    </p>
  </div>
  <div id="mainbody">
    <table class="tsel" border="0" width="100%">
      <tr>
        <td valign="top" align="center" width="50%">
          <table class="tsel" border="0">
            <tr>
              <td>
                <div class="selector" onclick="setwebcam()"
                     >相机</div>
              </td>
              <td>
                <div class="selector" id="qrimg" onclick="setimg()"    >
                  图库
                </div>
              </td>
            </tr>
            <tr>
              <td colspan="2" align="center">
                <div id="outdiv">
                </div>
              </td>
            </tr>
          </table>
        </td>
      </tr> 
      <tr>
        <td colspan="3" align="center">
          <div id="result">
          </div>
        </td>
      </tr>
    </table>
  </div>
  &nbsp;
</div>
<canvas id="qr-canvas" width="800" height="600">
</canvas>

body {
  width: 100%;
  text-align: center;
}

img {
  border: 0;
}

#main {
  margin: 15px auto;
  background: white;
  overflow: auto;
  width: 100%;
}

#header {
  background: white;
  margin-bottom: 15px;
}

#mainbody {
  background: white;
  width: 100%;
  display: none;
}

#footer {
  background: white;
}

#v {
  width: 320px;
  height: 240px;
}

#qr-canvas {
  display: none;
}

#qrfile {
  width: 320px;
  height: 240px;
}

#mp1 {
  text-align: center;
  font-size: 35px;
}

#imghelp {
  position: relative;
  left: 0px;
  top: -160px;
  z-index: 100;
  font: 18px arial, sans-serif;
  background: #f0f0f0;
  margin-left: 35px;
  margin-right: 35px;
  padding-top: 10px;
  padding-bottom: 10px;
  border-radius: 20px;
}

.selector { 
    margin: 0;
    border: 3px solid;
    padding: 0;
    cursor: pointer;
    padding: 15px;
 
}

#outdiv {
  width: 320px;
  height: 240px;
  border: solid;
  border-width: 3px 3px 3px 3px;
}

#result {
  border: solid;
  border-width: 1px 1px 1px 1px;
  padding: 20px;
  width: 70%;
}

ul {
  margin-bottom: 0;
  margin-right: 40px;
}

li {
  display: inline;
  padding-right: 0.5em;
  padding-left: 0.5em;
  font-weight: bold;
  border-right: 1px solid #333333;
}

li a {
  text-decoration: none;
  color: black;
}

#footer a {
  color: black;
}

.tsel {
  padding: 0;
}